Stevens was nominated by Republican President Gerald Ford. He joined the court in 1975 and retired in 2010, at 90.

Stevens was asked about speculation that 81-year-old Justice Ruth Bader Ginsburg is resisting calls from some liberals to retire while Barack Obama is president and Democrats control the Senate, which must confirm nominees.

"If you're interested in the job and in the kind of work that's done, you have to have an interest in who's going to fill your shoes," Stevens said.

Stevens said his decision to step down was made out of concern about his own health, rather than any political reason.